A lot of people want to lose weight, but struggle with it. I think I know why. Everybody's felt "hunger pangs", even if only a little bit. Well, I speculate that is because your gut bacteria are starting to die off. If you just eat fewer calories, your bacteria are going to start complaining that you're kill them, and you'll "feel like" eating more food.
That's why calorie-restriction diets don't work -- because you're *always* killing off your bacteria. But how can you lose weight unless you restrict calories? As dieticians are happy to tell you, "calories in - calories out = weight gain". But we're finding out that that's not true. It's when you spike your blood sugar that fat gets stored. If you eat the same amount of calories, but spread out over time (lots of small meals), or more conveniently, meals that include only foods that don't spike your blood sugar, then that energy will always be available to you for use, and none for storage.
But here's the problem: as long as you're eating any high-glycemic index foods, the bacteria that digest them will stay alive. And if you try to stop, they'll complain, and you'll always feel hungry. The key is to eat only low-glycemic index foods. That will kill off, once and for all, those bacteria that demand high-glycemic index foods.
So when you switch to a low-glycemic index foods (low carb, high fat, or LCHF), you'll still have the bacteria that love carbs, and they'll create gastic distress, hunger pangs, and loose motions. You need to presevere through this time. It's tolerable because it's just a few days. Once you kill them off (and it takes about five days to do that), you'll feel ordinary hunger pangs when you don't eat enough LCHF. And you'll start to lose weight.
There are two exceptions to eating high glycemic index foods. First, is that when you rip muscle tissue, your body will consume (rather than store) blood sugar to repair them. You can feel when you're doing this through your exercise. Not all exercise will do that. Sprinting usually will, or lifting more weights, or walking up more stairs. Second, binge day. Once a week you can binge on carbs. As long as it's just for one day, the carb-loving bacteria won't have a chance to start infesting your gut.
Note: I've gone through this transition several times, so I think I'm right. I don't know, however, of any studies that show that one type of bacteria thrives on carbs, while another type thrives on fat. Neither have I gone looking for any.